Research on the discrete element modeling method and tensile fracture behavior of the control unit stranded wire of Shearer cables

In addressing the mechanical response of the complex twisted structure of the control unit stranded wire of shearer cables, a modeling method based on Discrete Element Method (DEM) is proposed. This method incorporates nonlinear plastic deformation and the complex multi-body contact characteristics caused by twisting. In this study, a three-dimensional spatial model of the control unit stranded wire was developed and discretized into a discrete element model. Axial tensile loads were applied to the model, causing fracture, and the resulting stress-strain curve was compared with experimental tensile test results to validate the feasibility and accuracy of the discrete element model. Based on this model, the mechanical response of the control unit stranded wire under various factors, such as pitch and copper wire diameter, was studied. The results indicate that the stress-strain curves of the control unit stranded wire exhibit consistent trends across four different kinds of pitch. When the copper wire diameter was 0.39 mm and the pitch was 39 mm, 44 mm, 49 mm, and 54 mm, the corresponding tensile strengths were 294.00 MPa, 282.12 MPa, 268.56 MPa, and 266.16 MPa, respectively, while the fracture elongation rates were 26.94%, 26.24%, 25.84%, and 25.53%. Smaller pitch resulted in higher tensile strength and greater fracture elongation. When the pitch was greater than or equal to 49 mm, the influence of the pitch on the stress-strain curve diminished. When the pitch was 39 mm and the copper wire diameters were 0.25 mm, 0.30 mm, and 0.39 mm, the corresponding tensile strengths were 263.46 MPa, 272.58 MPa, and 294.00 MPa, and the fracture elongation rates were 23.93%, 24.49%, and 26.94%, respectively. Larger copper wire diameters led to higher tensile strength and greater fracture elongation. The stress-strain curves for wire diameters of 0.25 mm and 0.30 mm were relatively similar, while for a diameter of 0.39 mm, both the tensile strength and fracture elongation rate increased significantly, with the fracture elongation rate increasing by 12.58% compared to the 0.25 mm diameter. The study shows that smaller pitch and larger copper wire diameters result in higher fracture elongation rates and better ductility. The corresponding fitting curves are also provided. This research offers theoretical support and new insights for the study of the mechanical response of complex twisted structures.